Premixed asphalt composition and process for producing the same



Patented Nov 11, 1930 UNITED STATES JAMES snntny'nownnnn, or DALLAS, TEXAS nnmmxnnnsrnnm COMPOSITION AND rnocnss roar rnonoozme THE SAME;

V invention proposes a new and original processffor treatingfsuch adhesive mixtures was asphalt coated stone andasphalt coated sand when cooled to "agran'ular form so that .5 they ma be maintained in a granular'or high- ;1y ,dividedcondition without adhering or consolidating but which mixtures may atthe will Inf the operator be changed from non-adhesive mixtures .i-nto adhesive mixtures and consoli- 10 dated either bya slight' hea't process or cold under pressure, ,being thus reduced to final and ultimatecompaction. The invention also proposesa novel asphalt compound,

. 'Heretofore in this art of pavin'giwith as H 5 phaltlthe' mate-rialhas' been manufactured at a portable plant and has bieen-l'aidhot, or has been cooled and granulated and either laid cold or re-heated. After cooling and granu- :lating, such compounds, which may consist 2o of asphalt coated stone,,oriasphalt coated sand ,or the like, have been kept in a divided state.

reducing the 'cementitious and adhesive i properties of the asphalt cement vas by cutting thesamewith a volatile solvent or by .25 keeping the particles of coated mineral mattern divided with some sort of dust and by a other-expedients. ,7 Such an adhesivemixture is the ordinary sheet asphalt composition of sand and asphalt :zoor stone and asphaltzwhich'is in general use and is, under ordinary conditions, laid hot, but which-may be cooledto granular form.

, A particular and standard mixture known as sheet asphalt is composed of 85% of sand, 33 10% of asphalt and 5% of dust known as mineral filler. Thesand is dried and heated and vWhile hot is mixed with melted asphalt in a mechanical mixture so that each grain of )sand is coatedlor covered with asphalt and 40 the compound could be well described as asphalt coated sand. The dust or filler is'mixed in or'incorporated into th'ismixturein its dry state by me- 7 chani al stirring. 1 This po ition m y be ad granu a Ap pli cation ,filed March e, 1926; seri rno. 32,944.

plunging it into water after passing it a through a sieve and may be laid by re-heata 111g at a distance from the place of manufacture, but if stored will gradually consolidate of its own weight because or the heat of so a f a the sun when subjected thereto, or because of a pressure of the mass itself in storage; It often becomes set in cars or wagons during transportation so that it cannot be used and is therefore worthless, I A

The object of my invention is to put such composition, or compositions of like 'charaeter in such a condition that they may be shipped, stored and usedwithout adhering nntil fit is the will of the operator that they c be changed from non-adhesive mixtures to adhesive mixtures, whereupon they may be 7 spread, raked and rolled and consolidated in the form desiredby the operator either in sheetsor other form; i V

For the purpose of maintaining these .corn- 7: positions of mineral'aggregate and asphalt in anon-adl iesivestatel make use of the well knownproperty that a film .of water has for keeping asphalt surfaces from adhering and 7c thewell known property of deliquescent salts for absorbing moisture, even from the air, and thereby forming a liquid similartowater but of greateribody and coating quantity and It is apparent that water will keepthe particles separated and that they will not adhere as long as the surfaces are wet but water alone will not perform this service under vthe 7 conditions met. with in actual practice be: cause it drains away and the mass becomes dry or the film becomes so thin that adhesion or consolidation takes place, in hot dry air evaporation soon removes the water from the composition.

A deliquescent salt practically non-evaporative. I

has great avidity for 'Water and its dry crystals will take water from the air and change it from a dry salt to v a liqu d, aid liquid having a considerable g 7 coating capacity. Such a salt is calciumchlo ride (CaCl).- a I For practical purposes a solutionof calcium chloride containing 5.2 lbs; of calcium chloride to a gallon of Water isa practical solution forgeneraluse: I

Such-asolution With Water Wlll not evaporatefwill not drain away or run off the asphalt'particles, but will coat them with a, thin film Which has only slight adhesion.

This solution, thereforayvhen mixed With 7 i. cold, granulara'sphalt such as asphalt c foated "stone and the like-Will maintain it'in a state 'tiofladhesive it' may-be done" by treating it I withr a' solution of -ammonium oxalate, .(NH 0 0 1-11 0) which solution/Will V of division for the purpose of shipment'an'd v in, 1

application at'all normaltemperatures; i; 3

When it is desired to make'the composi precipitatejthe "mineral out lofo the calcium Chloride lpra ucingqa iinsolubl s l f on heating the'fwater'vvill"evaporate and "the rmm ium chloride'in .;the Water: Will de- 7 composegunder the I beat approximately 360 pass off Ias40:hh'iri'n'eij gas and ammonia 'gasfjlliOn'; evaporation 013,10 mils, ofaqueous solution it" leaves L004 w of fixed residue only,

said? solution being a 'jsat urated "solution 7 II f 'iii20. o

.' soI I i -the solution of calciumchloride is "thereby T nullified; and I the asphalt surfac s are free .,t,o-adhere,under pressuregf I l "The mixture' maybe-agitated cold vv'ith the "TheIsePamting an d'iiiiid'in'g "new "of ammonium oxalate and then warmed sufficiently to hasten' evaporation. Thesame *"carbonateof ammonium; s a 'VVhile these salts are pointed out .as. early- I V ing'out the principles of my inventiomother" chemicals will; immediately; suggest themselves to thez practical} chemist Which Will carry outgthej same principles under slightly difierentlconditions and costs. [It is pointed out that. the-methods of j applying; these solu- 5 l ar efmanyland quite apparent and vvill sugg t; themselves to a skilled person, but the mostefl'e'ctive is to'pass'the granulanas result may be obtained by the use 9f an- 1 other -salt such as sulphate, phos phate, or

phaltsithrough-a bath of the"so1ution,and

thejsolution of the precipitating agent may be sprinkled or flooded over'the Ioosegranu- I -lar mixt ure after itisplacedin situ in suf '7 fi'cientquantity to cause the proper chemical reactionandlchange the mixture into an adhesive one by destroying the. separating media. I o I v The residue of the operation an ad- V vantage to the. composition as this amorphous material is a very fine filling" agent 5 nd one required'in. asphalts as filler. y

Having thus described my process which 1' maybesubjected'to various forms and types,

such as weakening or-strengtheningthe solution to meet the requirementsof the age in a premixed condition. 1

, non-adhesive condition;

gregate asto size andcondition it is obvious I I that this'process may be, used for all sizes 7 of aggregate ofstone,vsand or slag and; all

conditions of adhesivemixtu're, either made. fromasphaltum or other binders of adhesive? o nature. 1 The advantage of my invention is obvious asit provides ameans for themanufacture of asphalt mixture at a central plant places fg and their shipment for use at distant {The process of manufacturing asphalt paving? mixtures which comprises lc' t ivering asphalt-coated grains with a solution ofcalgcium chlorid'e, thus coating the'particles and V preventing adhesionand' subsequently changij ingithezmixtureifrom a nonradhesive' state to 1 I w.

an adhesive state by treating the calcium f chloride {filinvwith I a precipitating ageiit bed; i I 3; Anfa sphaltcomposition in I a granular for'rncomposedof a'sphalt; an aggregate of v v mineral matter; and a t solution v of calcium ehlorideformingfa c oating rforthe granules.

' 4. A non' adhesiye granular asphalt com;

his"

position; adapted gtofbe transported while" I cold Vand'to bechangedlto'fanadhesive solidio- V fyingimi'xture at the vvill of :the operator by 0 the additionof ammoniumo'xalate and comprising dividedfinin'eral matter coated with asphalt and also havingthesurface of the asphalt] coated a solution of calcium H I I 5. A step i the process of man ef e asphalt gpaving mixt e h h q p l applying a; separating media made from-c211 ciumfl chloride to particles having an' asphalt surface for maint -ainin'gjthe part cles iin 'la' f 6.lTheprocejss of manufacturing i asphalt paving mixture jwhich' comprises coating asphalt-coat'ed aggregates with: a solution of calcium] chloride for'fmaintaining the as- 'phalt-coated aggregates wet and separated 1 [by a film jfof the solution, reacting 'withthecalcium chloride a precipitating salt which will render the asphaltecoated'aggregates ad hesive and capable of beingconsolidated into a stable and substantiallyrigidtmassfi. 1" p 7. vThe process of 'manu'facturing. asphalt, paving mixture which comprises separating soft adhesive asphalt-coated'particlesby,coat- V ingthe said particles 'vvith a calcium chlo-.

ride solution and then re-acting the calcium chloride solution with ammonium oxalate.

8. The process of manufacturing asphalt paving mixtures which comprises treating a mineral aggregate coated with an asphalt mixture with a division agent such as calcium chloride and subsequently re-acting with the division agent a precipitating agent that will produce with the division agent a substance capable of being evaporated and capable of leaving the original mixture of the mineral aggregate coated with the adhesive mixture in an adhesive state.

' JAMES SHELBY DOWNARD. 

